Patent Literature 1 discloses a configuration in which a pupil division function is provided by displacing a sensitivity region of a light receiving portion with respect to an optical axis of an on-chip microlens for a part of light receiving elements (pixels) of an image pickup element. These pixels are disposed at a predetermined interval between imaging pixel groups as focus detection pixels, and are configured to perform phase difference focus detection.
Patent Literature 2 discloses an image pickup apparatus that performs focus detection calculation by adding image data of focus detection pixel stored by a plurality of past reading in order to satisfy both a refresh operation with a short period and focus detection for an object with a low luminance.